[1] Univ Tennessee, Hlth Sci Ctr, Ctr Sickle Cell Dis, Memphis, TN USA
[2] Univ N Carolina, Dept Math & Stat, Charlotte, NC USA
[3] Univ N Carolina, Div Nephrol & Hypertens, Chapel Hill, NC 27515 USA
[4] Univ Illinois, Div Hematol Oncol, Chicago, IL USA
[5] St Jude Childrens Res Hosp, Dept Hematol, 332 N Lauderdale St, Memphis, TN 38105 USA
[6] Univ N Carolina, Div Gen Med & Clin Epidemiol, Chapel Hill, NC 27515 USA
[7] Duke Univ, Med Ctr, Duke Mol Physiol Inst, Durham, NC USA
[8] Univ N Carolina, Dept Biostat, Chapel Hill, NC 27515 USA
[9] Duke Univ, Med Ctr, Div Hematol, Durham, NC USA